Analysis of gasoline blending components



United States Patent 3,505,857 ANALYSIS OF GASOLINE BLENDING COMPONENTS Gilbert I. Jenkins, Ascot, England, assignor to The British Petroleum Company, Limited, London, England No Drawing. Filed Feb. 20, 1969, Ser. No. 801,186

Claims priority, application Great Britain, Feb. 28, 1968,

9,653/68 Int. Cl. G01n 33/22 US. Cl. 73-61 Claims ABSTRACT OF THE DISCLOSURE The RON, MON, RVP and SG of a low olefin, lead free gasoline blending component are determined by measuring the percentage of the component in each of 12 specified chemical groups and applying regression equations.

This invention relates to the analysis of gasoline blending components and in particular to a chromatographic method of determining the Research Octane Number of certain gasoline blending components.

The method according to the invention is suitable for use with gasoline blending components (hereinafter ca led the specified blending components) which contain only low concentrations of olefins and which are lead free. It is not applicable to blending components which contain a large proportion of olefins, e.g. blending components obtained by cracking. (Most finished gasolines cannot be analysed in accordance with the invention because they contain lead alkyl anti-knock agents and too great a proportion of olefins.)

The method according to the invention is particularly suitable for the analysis of the following four gasoline blending components:

LIGHT STRAIGHT RUN GASOLINES These are obtained by the distillation of crude petroleum and they consist predominantly of hydrocarbons which have 4-6 carbon atoms per molecule.

CATALYTIC REFORMATES MOTOR BENZOLES These have a high concentration of benzene, e.g. 60

100% by volume, and they are often obtained from a non-petroleum source.

' ISOMERIZATES These contain a large proportion of branched chain paraffins obtained by isomerization of straight chain paraifins.

As well as determining the Research Octane Number the method according to the invention can be used to determine the Reid Vapour Pressure, the Specific Gravity and the Motor Octane Number by a single experimental procedure. (It is pointed out that any one or any combination of this inspection data can be determined.)

The inspection data mentioned above, particularly the two octane ratings, require elaborate and time consuming procedures and a knowledge of the results is useful for controlling refinery plant and the method according to the invention makes the results available more quickly than conventional laboratory techniques. This increase in, speed is an advantage to plant operators.

According to the invention a method of analysing a sample of a specified gasoline blending component comprises:

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(a) Separating the sample into the following 12 groups,

Group 1: n-butane and all compounds more volatile than n-butane,

Group 2: all compounds less volatile than Group 1 and more volatile than Group 3,

Group 3: n-pentane,

Group 4: all compounds less volatile than Group 3 and more volatile than Group 5,

Group 5: n-hexane,

Group 6: all compounds less volatile than Group 5 and more volatile than Group 7,

Group 7: benzene,

Group 8: all compounds less volatile than Group 7 and more volatile than Group 9,

Group 9: toluene,

Group 10: all compounds less volatile than Group 9 and more volatile than Group 11,

Group H: all aromatic hydrocarbons whose molecule contains 8 carbon atoms (together with a few other compounds with boiling points in the same range),

Group 12: all compounds less volatile than Group 11, and

(b) Determining the quantity of material contained in each of the twelve groups. (Percentage by weight is a convenient system of measurement but any other system which gives the relative concentrations can be used.)

The Research Octane Number, Reid Vapour Pressure, Specific Gravity and Motor Octane Number can be calculated from the relative quantities obtained above by suitable linear regression equations. All the coefficients and the constant term may be derived statistically by using data obtained from a sufficient number of samples. If desired certain coefiicients can bederived from a knowledge of the properties of any pure compounds considered. From time to time results obtained by the method according to the invention should be checked by tests carried out in the laboratory by conventional techniques and the regression equations updated when necessary. The calculation can be carried out either by hand or by computer; the latter is convenient for closed loop control.

According to a preferred embodiment of the invention the separation is carried out chromatographically. This technique is particularly suitable for on-line use since automatic chromatographs are commercially available. These give results in digital form and they can be connected to provide direct input into a computer. The chromatographic method is relatively rapid and it can provide a set of results about 20 minutes after the injection of the sample.

Furthermore a chromatograph can provide results at frequent intervals, e.g. it can provide one set of results every 40 minutes.

The 12 groups specified above give accurate results but, if desired, more accurate results can be obtained, at the expense of more complicated regression equation, by dividing one or more of the groups specified above into two or more sub-groups. We will now give examples of such sub-division and, if desired, any one or more of these subdivisions may be utilised.

Group 1 This group could be split into two fractionsnamely n-butane and the remainder of the group.

Group 4 This group could be divided into two or three subgroups namely, 2-methyl pentane, 3-methyl pentane (or these two combined in a single sub-group) and the remainder of the group.

3 Group 6 This group could be divided into two sub-groups namely, methylcyclopentane and the remainder of the group.

Group 8 This group could be divided into from two to five subgroups namely, Z-methyl hexane, 3-methyl hexane (or these two combined in a single sub-group), 2:2:4-trimethyl pentane, n-heptane and the remainder of the group. (In cases where the concentration of 2:2:4-trimethyl pentane and/or n-heptane are high it is preferable to create a separate sub-group for whichever compound has the high concentration, or two sub-groups if both have high concentrations. The compound with the low concentration, or both compounds it both have low concentrations, is conveniently comprised in the remainder.)

Groups 11 and 12 If desired individual aromatic compounds contained within these groups could be used as sub-groups which contain a single compound. In some cases it may be desirable to use a sub-group which contains more than one compound, e.g. a sub-group which contains all the xylenes.

By Way-of example nine different gasoline blending components were chosen for analysis in accordance with the invention.

A sample of each was separated chromatographically into the twelve groups defined above and the Research Octane Number (RON), Reid Vapour Pressure (RVP), Specific Gravity (SG) and Motor Octane Number (MON) were obtained using the regression equations given in Table 1. (In these equations Gn is used to designate the percent by weight in the nth group.)

The experimental results are given in Table II which shows the percent by weight in each group for each sample, the RON, RVP, SG and MON as calculated from these percentages and, for the sake of comparison the RON, RVP, SG and MON as obtained by conventional laboratory tests.

TABLE 1 these is not calculated a complete regression equation for MON can be obtained by substitution for RON and SG.

(a) Separating the sample into the following 12 groups,

Group 1: n-butane and all compounds more volatile than n-butane, Group 2: all compounds less volatile than Group 1 and more volatile than Group 3, Group 3: n-pentane, Group 4: all compounds less volatile than Group 3 and more volatile than Group 5, Group 5: n-hexane, Group 6: all compounds less volatile than Group 5 and more volatile than Group 7, Group 7: benzene, Group 8: all compounds less volatile than Group 7 and more volatile than Group 9, Group 9: toluene, Group 10: all compounds less volatile than Group 9 and more volatile than Group 11, Group 11: all aromatic hydrocarbons whole molecule contains 8 carbon atoms (together with a few other compounds with boiling points in the same range), Group 12: all compounds less volatile than Group 11, (b) Determining the quantity of material contained in each of the twelve groups, and (c) Calculating, from suitable regression equations which utilise the quantities determined in (b), at least one of the Research Octane Number, Reid Vapour Pressure, Specific Gravity, Motor Octane Number and a control parameter suitable for controlling a plant producing the gasoline blending component. 2. A method according to claim 1 in which Group 1 is split into two sub-groups, namely:

n-butane and the remainder of the group. 3. A method according to claim 1, in which Group 4 is divided into two sub-groups namely:

2-methyl pentane toegther with 3-methyl pentane, and the remainder of the group. 4. A method according to claim 1, in which Group 4 is divided into three sub-groups namely:

Z-methyl pentane, 3-methyl pentane, and the remainder of the group. 5. A method according to claim 1, in which Group 6 is divided into two sub-groups namely:

methyl-cyclopentane, and the remainder of the group.

TABLE II Total Light Heavy catalytic catalytic catalytic Motor 05 Cs/Oa 4 Crude Straight run reiormate reformate reformate benzole isomerizate isomerizate isomerlzate n-pentane gasoline 0.4 1.9 0.0 0.0 0.3 0.5 1.0 0.0 0.0 8. 4 11. 6 0. 3 O. 0 95. 8 28. 5 0. 5 7. 5 8. 1 6. 4 9. 2 0. 3 0. 0 3. 9 10. 5 0. 5 91. 5 30. 5 11. 4 23. 1 1. 2 0. 0 0. 0 55.0 88.0 1. 0 25. 9 4. 2 9. 8 0.4 0. 0 0. 0 5. 5 9. 0 0. 0 20. 1 0.9 2.5 0.6 0.2 0.0 0.0 1.0 0.0 4.4 6.8 6. 1 0.3 67. 3 0. 0 0. 0 0. 0 0. 0 0. 5 5. 7 25. 1 6. 0 1. 3 0. 0 0. 0 0. 0 0. 0 10. 5 22. 0 10. 2 18. 1 19. 6 0. 0 0. 0 0. 0 0. 0 0. O 1.0 0.4 2.3 0.2 0.0 0.0 0.0 0.0 0.0 23. 7 0. 0 34. 0 7. 0 0. 0 0. 0 0. 0 0. 0 0. 0 9. 0 0. 0 36. 5 2. 6 0. 0 0. O 0. 0 0. 0 0. 0 96. 2 73. 6 101. 2 110. 4 92. 5 83. 6 80. 6 65. 0 64. 0 95. 6 72. 4 101. 4 110. 3 92. 5 32. 3 80. 5 64. 9 63. 4 0. 773 0. 682 0. 839 0. 874 0. 625 0. 649 0. 663 0. 625 0. 659 0. 776 0. 696 0. 834 0. 872 0. 624 0. 640 0. 652 0. 624 0. 657 85. 0 72. 5 9.0 99. 8 88. 0 81. 6 80.4 71.0 62. 5 87. 5 69. 9 91. 2 97. 8 2 77. 5 65. 1 63. 2 6. 3 1 15. 9 6. 1 1 1 16. 2 a, 0. 773 0. 682 0. 839 O. 874 0. 663 0. 625 0. 659

I claim: I

1. A method of analysing a sample of a low olefin content, lead free gasoline blending component which comprises:

6. A method according to claim 1, in which Group 8 is divided into two sub-groups namely:

Z-methyl hexane together with 3-methyl hexane, and

the remainder of the group.

5 6 7. A method according to claim 6, in which Group 8 is 10. A method according to claim 1, in which stage '(c) divided into four sub-groups namely: uses linear regression equations.

Z-methyl hexane together with 3-methyl hexane,

2:2 :4-trimethyl pentane, References Cited 3 2 g the group 5 UNITED STATES PATENTS re 21111 e 8. A method according to claim 1, in which there is an 4/1969 Ayers at additional sub-group WhlCh contains all the Xylenes. LOUIS R. PRINCE, Primary Examiner 9. A method according to claim 1 in which the separation is carried out chromatographically. 10 J. W. ROSKOS, Assistant Examiner mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. Q QQQ QQZ Detcd :11 1219 Invcntorh) Gilbert IVOI. Jenkins It in certified that error eppeete in tho above-identified patent and that aid Letters Patent ere hereby corrected ee shown below:

Table II, left-hand column, fifteenth line counting from "61" as line 1, for "SSW/60F"- read --SG 60/60F kpt";

Table II, colmn headed "Heavy Catalytic Reformste", line 17 captioned "HON Dcpt" for "9.0" read --90.0--;

Table II, delete the last line; and

Column 4, line 18, for "whole" read --whose--.

smmzflun swan ssp'z's' 1970 an) M Edwfl'a ll. Bil-11. Amsting 0mm mm I. am, JR. 

